ORGANIZATION AND SIGINIFICANT ACCOUNTING POLICIES - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 127,168,000	$ 214,363,000
Restricted cash	36,837,000	32,349,000
Total cash, cash equivalents and restricted cash	$ 164,005,000	$ 246,712,000	$ 112,723,000	$ 94,425,000